Hey! I use and LOVE Estes marine sand. I have the black and the white. Great stuff!! just goggle it to find. And a good size tank is at least 2 feet wide. I've breed motoros in a 210(7x2x2) They can breed at a disk size of 12inch for female. And whenever the male is mature witch is around 10-12inches most of the time. The best combo to start with is like 3 females and 2 males. And age comes into play with water changes and feeding. Like take great care of them. And they grow much faster. any other questions please lemme know